Manufacture of aluminum chlorid.



. UNITED s ATEs PATENT OFFICE.-

nm nonurm mums, or ron'r an-r'nna, 'rnxas, ASSIGNOB TocU r nnrm mo comm, or PITTSBURGH, rnmrsuvama, a coarona'non or TEXAS.

MANUFACTURE OF ALUMINUM CHLOBID.

No Drawing.

To all-whom it may concern Be it known that I, ALME'R MoDnrm MCAFEE, a citizen of the United States, residing at Port Arthur, in the county of Jefferson and State of Texas, have invented certain new and useful Improvements in the Manufacture of Aluminum Ohlorid, of which the following is a specification.

This invention relates to the manufacture of aluminum chlorid; and it comprises a method of making aluminum chlorid wherein bauxite, or ot e'r form of hydratedalumina, without removing its water of hydration, is intimately commingled with a caking or coking coal formed into briquets, any suitable binder being used, and the briquets coked, such briquets being then exposed to the action of heat and chlorin, or chlorin containing gas, such as HCl, or a mixture. of HCl and a reducing gas, the aluminum chlorid formed being recovered by cooling the sublimed vapors; all as more fully hereinafter set forth and as claimed.

While in principle the operation of mak ing aluminum chlorid in the anhydrous form by passing chlorin-over a mixture of carbon and alumina at a high temperature is simple enough, in practice there are many difiiculties when working on the large scale. Many of these difliculties reside in the fact that it is hard to produce an intimate contact of the carbon with the alumina and of the chlorin with both. Both carbon and alumina are infusible materials and theirgether they must be ground, in the ordinary operation, not only very fine but to induce reaction the temperature must be raised to a very high degree; a temperature at which the retorts. suffer more or less under the conjoint action of the chlorin and carbon. Further, it is found in practice that heating the alumina to too high a temperature lessens reactivity in making aluminum chlorid.

And with very fine and intimate pulveru Specification of Letters Intent.

Patented Feb. 27.1917.

Application filed September 29, 1816. Serial No. 122,869.

lent mixtures of alumina and carbon therearise draft difficulties in passing chlorin through the mass.

By reason of the difiiculties stated, it has become the practice to make either the double chlorid of aluminum and sodium in which these difliculties do not exist to so great an extent, "or to make the aluminum chlorid from metallic aluminum and chlozin; which is a relatively expensive operaion.

I have found however that by a certain particular procedure I can obviate' the noted difliculties and attain a number of new advantages. In this method, I produce the necessary intimate contact between the alumina and the carbon by using a fat or rich coal of the nature of those called coking or cakingcoals. The coking coal and thealumina are first ground to a very fine powder, say about 100 mesh, although finer may be used with advantage and somewhat coarser is susceptible of use. The two powders are next mixed very intimately. The amount of coal is so selected that after coking it will yield the amount of carbon necessary to reduce the alumina with about 20 per cent. excess. The mixture is next formed into briuets or cakes under high pressure. In so oing, a temporary binder, such as molasses, sticky petroleum products, retort residues, asphalts, etc., is advantageously used. There is room, however, for much choice in these materials. It is desirable to use for the temporary binder something havinga maximum stickiness since it is desirable to reduce the quantity as much as possible; and also the binder should be one which will persist until the coal begins to coke. The choice in quantity .and quality of binder, however, depends somewhat on the particu lar coal used. The best binder I have found is a special gumm product, somewhat like then added and heating and stirring con-.

tinued until the mixture is sufiiciently intimate. This mixture is then briqueted under heavy pressure to give as dense a product as possible, A pressure of about 4000 ounds works well. The briquets are next 0 arged so .tion may be in any type of retort, the re-.

into a hot retort and ooked at a temperature sufiiciently high to drive off the water of hydration and coke the coal, care beingtaken that it is not high enough to cause the bauxite to become dense and chemically inert,

of the anhydrous kind, that is, deh drate bauxite or the like, the briquets wil be en tirel too dense; neither is the briquetso' 'gro need as reactive with chlorin as. ""a riquet made with hydrated alumina. Using bauxite or hydrated alumina in the coking operation the alumina dehydrates and makes the material orous; this porosity extending to the partic es of alumina in the mixture.

' That is, the final briquet is not only more porous considered'as a'briquet but the very fine carbon-permeated alumina particles in the briquet are in themselves also porous. f.

I find this quite a necessary conditioiito. et

the best results. As the hydrated alumina may be used, ordinary commercial undehydrated bauxite or any other native form of hydrated alumina. may be used, such as diaspore, gibbsite, etc. As bauxite comes from" the mines it carries 8 to '12 per cent.

of what may be termed physical moisture;

1t ismore or less damp. In addition it carries around 30 per cent. of chemically combinedwater which is water of hydra- .tlon. It is this water of hydration which I find it necessary to retain in the material,

but I ordinarily dry the crude bauxite so as to get ridof the moisture mechanically present.

The briquets made as described may be coked in any of th'e usual coking furnaces. After the coking they may be treated with.

1 chlorin in any form of retort made of a good refractory clay. Vitrified clay retorts are best. These retorts may be heated in any suitable manner, either internally or externally.

- I have found that with briquets made as described the chlorinating'action goes on at 1600 to 18009 F. although temperatures a little above and a little below this may be used. But I find there is no great increase 1n the speed of the reaction at temperatures much above this; the alumina becoming less reactive through internal changes, while temperatures much above this are hard on the retorts. While, as stated, the chlorinaactivity of the mixture made as described renders posslble the use of vertical retorts -hydrated bauxite and cokin I find it advantageous'to use a type of vertical retort in which I introduce chlorin or hydrochloric acid 'gas at the top and remove vapors of aluminum chlorid at the bottom. This mode of introduction is in accordance with specific gravities of the chlorin gas and the aluminum chlorid vapors and contributes materially to a smooth and uniform operation with a maximum utilization of both chlorin and alumina.

With'the' proportions stated the briquets substantiall '-all disappear, there being a esid ue of ree carbon and ash; this ash bethe coal and impurities inthe The a chlorid formed contains some-iron chlorid and, sometimes, a little titanium chlorid where the crude bauxite has been used. It may be employed as such for oil conversion and many other actions in which the. catalytic properties of anhydrous aluminum chlorid are utilized and in which the presence of these bodies is immaterial. If for any reason it is to be purified, this may be-done by resublimation.

-Whe re"af';pure aluminum chlorid is desired',ithe bauxite used may be initially purified to-flree' it' of iron, titanium, etc., by any of. thewell known methods, such as heating with caustic soda solutions, etc. Or specially prepared pure, artificial alumina hydrates 'may be used; -But for most purposes I can tak ethe crude bauxite as it comes from the mines.

What I claim v 1. In 'the manufacture of aluminum chlorid the process which comprises intimately incorporating finely divided hydrated alumina and coking coal, coking the mixture and treating with chlorin.

2. In the manufacture of aluminum chlorid the process which, comprises intimately incorporating finely divided undecoal, coking the mixture and treating wit chlorin.

3. In, the manufacture of aluminum chlorid the process which comprises. intimately incorporating finely divided hydrated alumina, coking coal and a temporary binder, coking the mixture and treating with chlorin.

4. In. the manufacture of aluminum chlorid the process which com rises intimately incorporating finely divi ed undehydrated bauxite, coking coal and a temporary binder, coking the mixture and treating with chlorin.

5. In the manufacture of aluminum chlorid the process which comprises intimately' incorporating finely divided hydrated alumina and cokin coal, coking the mixture: and treating wit gas comprising chlorin. 4

6. In the manufacture of aluminum chlorid the process which comprises intichlorid the process which comprises inti-" mately incorporating finely divided hydrated alumina, coking coaland a temporary binder, coking the mixture and treat 10 ing with gas comprising chlorin.

. 8. In the manufacture of. aluminum hydrated bauxite, coking coal and a temporary binder, coking the mixture and treating with gas comprising chlorin. g

In testimony whereof, I aflix my signature. I I v ALMER MODUFFIE MQAFEE. Witnesses:

GEORGE H. TABER, Wnsmg A. Loozmr,

'chlorid the process. which comprises inti- Q Inately incorporating finely divided unde- 

